Impact of MRI-based planning in transperineal interstitial brachytherapy for vaginal-involving tumors.

Purpose: The purpose of the study was to analyze patients with vaginal-involving recurrences of gynecological tumors and primary vaginal tumors, treated with transperineal interstitial brachytherapy (P-ISBT). Dosimetric, clinical, and toxicity analysis of these patients was conducted, incorporating MRI in volume definition and dose-volume dosimetry.

Material And Methods: Forty-two patients were retrospectively analyzed.

High-dose-rate (2 fractions of 13.5 Gy) and low-dose-rate brachytherapy as monotherapy in prostate cancer. Long term outcomes and predictive value of nadir prostate-specific antigen.

Purpose: This study aims to evaluate the outcomes of patients treated for low-risk (LR) and favorable intermediate risk (FIR) prostate cancer with brachytherapy (BT) in monotherapy with LDR or HDR and its relationship with nadir PSA (nPSA).

Materials And Methods: We retrospectively analyzed 139 patients (2005-2019) with exclusive LDR (46%. 145/160 Gy) /HDR (54%.

An efficient component of the redundancy calibration program to ensure equipment stability by assaying HDR Ir-192 sources at the time of replacement.

Background: Brachytherapy (BT) treatments involving temporary high-dose rate (HDR) sources are extensively employed in clinical practice. Ensuring the consistency of all measurement equipment at the hospital level is crucial, requiring a robust redundancy and consistency program. This enables the institution to verify the stability of the dosimetry system over time.

A single center, inter-observer evaluation of vestibular schwannoma stereotactic radiosurgery and its dosimetric impact.

The aim of this work was to evaluate the inter- and intra-observer variation in contouring vestibular schwannoma (VS) and the organs-at-risk (OAR), and its dosimetric impact in Volumetric Modulated Arc Therapy (VMAT). Three VS typical cases were contoured by four clinicians. The Agreement Volume Index (AVI) appeared to be notably higher in VS than in OARs, such that the dose coverage of VS is fairly robust.

Characterization of Plastic Scintillator Detector for In Vivo Dosimetry in Gynecologic Brachytherapy.

(1) Background: High dose gradients and manual steps in brachytherapy treatment procedures can lead to dose errors which make the use of in vivo dosimetry (IVD) highly recommended for verifying brachytherapy treatments. A new procedure was presented to obtain a calibration factor which allows fast and robust calibration of plastic scintillation detector (PSD) probes for the geometry of a compact phantom using Monte Carlo simulations. Additionally, characterization of PSD energy, angular, and temperature dependences was performed.

Free automatic software for quality assurance of computed tomography calibration, edges and radiomics metrics reproducibility.

Purpose: To develop a QA procedure, easy to use, reproducible and based on open-source code, to automatically evaluate the stability of different metrics extracted from CT images: Hounsfield Unit (HU) calibration, edge characterization metrics (contrast and drop range) and radiomic features.

Methods: The QA protocol was based on electron density phantom imaging. Home-made open-source Python code was developed for the automatic computation of the metrics and their reproducibility analysis.

A User-Friendly System for Mailed Dosimetric Audits of Ir or Co HDR Brachytherapy Sources.

Objectives: The main goal of this work is to design and characterize a user-friendly methodology to perform mailed dosimetric audits in high dose rate (HDR) brachytherapy for systems using either Iridium-192 (Ir) or Cobalt-60 (Co) sources.

Methods: A solid phantom was designed and manufactured with four catheters and a central slot to place one dosimeter. Irradiations with an Elekta MicroSelectron V2 for Ir, and with a BEBIG Multisource for Co were performed for its characterization.

HDR brachytherapy in keratinocyte skin carcinomas - Single center experience with analysis of clinical, dosimetric, and radiobiological factors in acute skin toxicity.

Purpose: Radiotherapy techniques have been utilized to treat keratinocyte skin carcinoma (KSC). The objective of this study was to report the results of patients with KSC treated with HDR brachytherapy, with a variety of techniques and applicators. A statistical analysis of clinical, radiobiological, and technical factors has been made to analyze those factors related to skin acute toxicity, focused on acute epithelitis G3.

Ciliary body medulloepithelioma treated with intra-operative brachytherapy after fine needle aspiration biopsy.

Medulloepithelioma is the second most common type of pediatric intra-ocular tumors. It commonly arises from ciliary body, and it is generally diagnosed in the first decade of life. Management options for medulloepithelioma include enucleation, resection, or radiotherapy, but further investigation is still needed.

GEC-ESTRO ACROP recommendations on calibration and traceability of HE HDR-PDR photon-emitting brachytherapy sources at the hospital level.

The vast majority of radiotherapy departments in Europe using brachytherapy (BT) perform temporary implants of high- or pulsed-dose rate (HDR-PDR) sources with photon energies higher than 50 keV. Such techniques are successfully applied to diverse pathologies and clinical scenarios. These recommendations are the result of Working Package 21 (WP-21) initiated within the BRAchytherapy PHYsics Quality Assurance System (BRAPHYQS) GEC-ESTRO working group with a focus on HDR-PDR source calibration.

Evaluation of dosimetric effects of metallic artifact reduction and tissue assignment on Monte Carlo dose calculations for I prostate implants.

Purpose: Monte Carlo (MC) simulation studies, aimed at evaluating the magnitude of tissue heterogeneity in I prostate permanent seed implant brachytherapy (BT), customarily use clinical post-implant CT images to generate a virtual representation of a realistic patient model (virtual patient model). Metallic artifact reduction (MAR) techniques and tissue assignment schemes (TAS) are implemented on the post-implant CT images to mollify metallic artifacts due to BT seeds and to assign tissue types to the voxels corresponding to the bright seed spots and streaking artifacts, respectively. The objective of this study is to assess the combined influence of MAR and TAS on MC absorbed dose calculations in post-implant CT-based phantoms.

Review on Treatment Planning Systems for Cervix Brachytherapy (Interventional Radiotherapy): Some Desirable and Convenient Practical Aspects to Be Implemented from Radiation Oncologist and Medical Physics Perspectives.

Intracavitary brachytherapy (BT, Interventional Radiotherapy, IRT), plays an essential role in the curative intent of locally advanced cervical cancer, for which the conventional approach involves external beam radiotherapy with concurrent chemotherapy followed by BT. This work aims to review the different methodologies used by commercially available treatment planning systems (TPSs) in exclusive magnetic resonance imaging-based (MRI) cervix BT with interstitial component treatments. Practical aspects and improvements to be implemented into the TPSs are discussed.

In Vivo Verification of Treatment Source Dwell Times in Brachytherapy of Postoperative Endometrial Carcinoma: A Feasibility Study.

(1) Background: In brachytherapy, there are still many manual procedures that can cause adverse events which can be detected with in vivo dosimetry systems. Plastic scintillator dosimeters (PSD) have interesting properties to achieve this objective such as real-time reading, linearity, repeatability, and small size to fit inside brachytherapy catheters. The purpose of this study was to evaluate the performance of a PSD in postoperative endometrial brachytherapy in terms of source dwell time accuracy.

A Monte Carlo study of the relative biological effectiveness in surface brachytherapy.

Purpose: This work aims to simulate clustered DNA damage from ionizing radiation and estimate the relative biological effectiveness (RBE) for radionuclide (rBT)- and electronic (eBT)-based surface brachytherapy through a hybrid Monte Carlo (MC) approach, using realistic models of the sources and applicators.

Methods: Damage from ionizing radiation has been studied using the Monte Carlo Damage Simulation algorithm using as input the primary electron fluence simulated using a state-of-the-art MC code, PENELOPE-2018. Two Ir rBT applicators, Valencia and Leipzig, one Co source with a Freiburg Flap applicator (reference source), and two eBT systems, Esteya and INTRABEAM, have been included in this study implementing full realizations of their geometries as disclosed by the manufacturer.

Evaluation of the impact of EMBRACE II protocol in Spanish centers, with a large cohort of patients using a ranking index.

Purpose: The aim of this paper was to assess development of high-dose-rate (HDR) cervix brachytherapy (BT) implants in three Spanish institutions before and after introduction of EMBRACE II protocol.

Material And Methods: 392 patients from three different institutions, treated between 2009 and 2019 were analyzed. D of high-risk clinical target volume (HR-CTV) and D of organs at risk (OARs) of all patients were collected.

Embedded bleeding detector into a PMMA applicator for electron intraoperative radiotherapy.

Purpose: The aim of this work is to present a ready to industrialize low-cost and easy-to-install bleeding detector for use in intraoperative electron radiation therapy (IOERT). The detector works in stand-alone mode and is embedded into a translucent polymethylmethacrylate (PMMA) applicator avoiding any contact with the patient, which represent a novelty compared to previous designs. The use of this detector will prevent dose misadministration during irradiation in the event of accumulation of fluids in the applicator.

Evaluation of intrafraction motion with an open immobilization mask for HyperArc treatment of multiple brain metastases.

Purpose: In the implementation of the use of Encompass partially open immobilization mask to perform SRS of multiple brain metastasis, the evaluation of patient's intrafraction motion (IM) is deemed convenient to verify that the margins applied to the GTV are able to ensure adequate dose coverage to each lesion.

Methods: IM was determined by comparing the pre- and post-treatment CBCT images with respect to the simulation CT for a total of 23 fractions. The dosimetric impact on GTV coverage due to translational errors in patient positioning and rotational uncertainties of LINAC's performance was also evaluated.

Source strength determination in iridium-192 and cobalt-60 brachytherapy: A European survey on the level of agreement between clinical measurements and manufacturer certificates.

Background And Purpose: Brachytherapy treatment outcomes depend on the accuracy of the delivered dose distribution, which is proportional to the reference air-kerma rate (). Current societal recommendations require the medical physicist to compare the measured values to the manufacturer source calibration certificate. The purpose of this work was to report agreement observed in current clinical practice in the European Union.

Feasibility and potential advantages using VMAT in SRS metastasis treatments.

Background: Utilization of stereotactic radiosurgery (SRS) for brain metastases (BM) has become the technique of choice as opposed to whole brain radiation therapy (WBRT). The aim of this work is to evaluate the feasibility and potential benefits in terms of normal tissue (NT) and dose escalation of volumetric modulated arc therapy (VMAT) in SRS metastasis treatment. A VMAT optimization procedure has therefore been developed for internal dose scaling which minimizes planner dependence.

Low-/high-dose-rate brachytherapy boost in patients with intermediate-risk prostate cancer treated with radiotherapy: long-term results from a single institution team experience.

Purpose: To compare brachytherapy (BT) boost of low-dose-rate (LDR) and high-dose-rate (HDR) techniques in patients diagnosed with intermediate-risk prostate cancer.

Material And Methods: Between January 2005 and February 2018, 142 patients (50 LDR and 92 HDR) with intermediate-risk prostate cancer were treated with a BT boost, and retrospectively analyzed. Prescribed dose was 45 Gy with external beam radiotherapy (EBRT) plus 100-108 Gy with LDR-BT, and 60 Gy with EBRT plus one fraction of 10 Gy with HDR-BT.

Surface brachytherapy: Joint report of the AAPM and the GEC-ESTRO Task Group No. 253.

The surface brachytherapy Task Group report number 253 discusses the common treatment modalities and applicators typically used to treat lesions on the body surface. Details of commissioning and calibration of the applicators and systems are discussed and examples are given for a risk-based analysis approach to the quality assurance measures that are necessary to consider when establishing a surface brachytherapy program.

Phantom development for daily checks in electron intraoperative radiotherapy with a mobile linac.

Purpose: IORT with mobile linear accelerators is a well-established modality where the dose rate and, therefore, the dose per pulse are very high. The constancy of the dosimetric parameters of the accelerator has to be checked daily. The aim of this work is to develop a phantom with embedded detectors to improve both accuracy and efficiency in the daily test of an IORT linac at the surgery room.

Depth-dose measurement corrections for the surface electronic brachytherapy beams of an Esteyaunit: a Monte Carlo study.

Three different correction factors for measurements with the parallel-plate ionization chamber PTW T34013 on the Esteya electronic brachytherapy unit have been investigated. This chamber type is recommended by AAPM TG-253 for depth-dose measurements in the 69.5 kV x-ray beam generated by the Esteya unit.